The number of sexual offenses on subways in Seoul leaped by more than 20 percent last year, government data showed Tuesday.

From 848 cases of sex crimes on the Seoul subway in 2012, the figure rose to over 1,000 cases in 2013, a 20.1-percent increase, according to data from the Ministry of Gender Equality and Family and the Seoul Metropolitan Police Agency.

The number of people arrested on sexual offense charges also rose by 19 percent between 2012 and 2013.

Over half of the crimes occurred during rush hour, with 28 percent of the crimes occurring from 8 a.m. to 10 a.m. and 23.5 percent from 6 p.m. to 8 p.m. Subway Line 2 saw the most sexual offenses with over 30 percent, followed by Line 4 at 18.3 percent and Line 1 at 17.5 percent. Line 2 is the most crowded Seoul subway line, and accounts for almost half of the subway sexual assault cases in the past three years.

The Gender Ministry and the Seoul police will hold a joint campaign against sex crimes in 15 subway stations during peak commuting times on Wednesday.